A soldering apparatus is widely used to weld electronic components on a printed wiring board. FIG. 1 is a schematic perspective view illustrating a conventional soldering apparatus. As shown in FIG. 1, the conventional soldering apparatus 1 comprises a transmission mechanism 11 and a soldering oven 12. The transmission mechanism 11 comprises an outlet 110, two tracks 111 and two conveyor belts 112. The two conveyor belts 112 are in parallel with each other and movably disposed on the two tracks 111. The two conveyor belts 112 are used for transporting a printed wiring board 2 along with electronic components (not shown) into the soldering oven 12. After the printed wiring board 2 is introduced into the soldering oven 12, a reflow soldering process is performed to weld the electronic components on the printed wiring board 2. The soldering oven 12 comprises an inlet 120, an outlet 121 and an output mechanism 13. The output mechanism 13 comprises two guide rails 131, two link belts 132 and a guide rail adjusting member 133. The two link belts 132 are in parallel with each other and movably disposed on the two guide rails 131, respectively. After the printed wiring board 2 is introduced into the soldering oven 12, the two link belts 132 are driven by a motor (not shown) to support the printed wiring board 2 and move the printed wiring board 2 in the direction A. Consequently, the reflow soldering process can be performed by the soldering oven 12. The guide rail adjusting member 133 is disposed over the two guide rails 131 and linked with the two guide rails 131. The two guide rails 131 are movable relative to the guide rail adjusting member 133, so that the distance between the two guide rails 131 is adjustable.
FIG. 2 is a schematic view illustrating the relationship between the transmission mechanism and the reflow oven of the conventional soldering apparatus of FIG. 1. As shown in FIG. 2, before the reflow soldering process is performed, the operator has to manually adjust the output mechanism 13 of the soldering oven 12. In particular, by manually adjusting the guide rail adjusting member 133, one guide rail 131a of the two guide rails 131 is horizontally moved in the direction B1. Consequently, the distance d2 between the two guide rails 131 is equal to the distance d1 between the two tracks 111 of the transmission mechanism 11 (i.e., the width w of the printed wiring board 2). After the distance d2 between the two guide rails 131 is manually adjusted, the printed wiring board 2 is placed on the two tracks 111 of the transmission mechanism 11. Consequently, the printed wiring board 2 is transported to the outlet 110 by the two conveyor belts 112. Then, the printed wiring board 2 is transported to the output mechanism 13 of the soldering oven 12. Then, the printed wiring board 2 is transported into the soldering oven 12 by the two link belts 132, so that the reflow soldering process is performed. Then, the printed wiring board 2 with the mounted electronic components is outputted from the outlet 121.
As mentioned above, the distance d2 between the two guide rails 131 of the soldering oven 12 can be adjusted according to the width w of the printed wiring board 2 before the reflow soldering process is performed. Although the distance d2 between the two guide rails 131 of the soldering oven 12 is adjustable, the conventional soldering apparatus 1 has no mechanism for aligning the two guide rails 131 with the two tracks 111 of the transmission mechanism 11. Consequently, after the distance d2 between the two guide rails 131 and the distance d1 between the two tracks 111 of the transmission mechanism 11 are adjusted to be equal to the width w of the printed wiring board 2 by the operator, there is a slight misalignment between the two guide rails 131 and the two tracks 111. When the printed wiring board 2 is transported to the outlet 110 of the transmission mechanism 11 and the inlet 120 of the soldering oven 12, the external forces applied to the bilateral sides of the printed wiring board 2 are not balanced because of the misalignment. The unbalanced external forces may cause the vibration of the printed wiring board 2. Under this circumstance, the printed wiring board 2 is rocked and fails to lie flat. Since the printed wiring board 2 fails to be smoothly transported through the soldering oven 12, the printed wiring board 2 possibly drops down or escapes from the soldering apparatus 1. In other words, the misalignment may adversely affect the subsequent reflow soldering process, reduce the product yield and decreases the throughput.
Therefore, there is a need of providing a soldering apparatus with an automatic aligning function in order to eliminate the above drawbacks.